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Rocket Mass Heater for a Greenhouse?  RSS feed

 
Lindsey Schiller
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Posts: 32
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Hi,

I'm trying find some best practices for incorporating a rocket mass heater in a greenhouse. Greenhouses are extremely leaky structures (much higher rates of air infiltration than any home). I can imagine the heater would create additional cold air infiltration -- sucking heat into the heater and pumping it outside. Cold air will naturally be drawn into the structure.

I've seen a post commenting that their air intake came from the outside. That's a huge compromise in efficiency as well, but perhaps not as great. It seems rocket mass heaters have such a high temperature, they can still heat very cold intake air to the same level as pre-warmed (indoor) air, without much difference in performance? That is just my guess.

Greenhouses are also very humid environments. I don't know if that extra humidity could be an issue in the exhaust pipe. Is water vapor in the exhaust pipe generally a problem in the first place?

Any other general recommendations for tailoring this system to a greenhouse application would be helpful. Thanks in advance.
Lindsey
 
allen lumley
pollinator
Posts: 4154
Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''
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Lindsey S. : Kinda in order , leaky is good, but extremely little heat Energy is lost up the Chimney - With a properly balanced Amount of Thermal Mass

To the size of Your Rocket Burner Base your final exhaust time will be in the 100ºƒ - to - 150ºƒ You could consider your Thermal Mass as being like

Robin Hood, the Rocket Combustion Core, Delivers up its treasure of heat and Your mass goes to work to spread it around the surrounding area with

very little loss. Win (1)


In fact the J-Tube style actually functions in the same manner as the S-Trap under your sink and blocks the leakage of Heat Energy when the Fire

goes out Win 2

And then also is the fact that your Rockets thermal mass keeps working all night long with no need for you to be there- an extra 'eye' on the place

that doesn't cost you a dime (extra ) Win 3 And when you get there in the morning its still warm ! Win 4

You can build your greenhouses Thermal mass into the floor, or as a bench off of the ground where you can baby your starter plants /seed beds,

all without ever having to bend over to work on them -or BOTH ! Another Win this one for your Back !

A well build Rocket that has come up to temperature will pump much of the Excess moisture in Your Greenhouse out through your final exhaust,

another part of the Moisture is absorbed into the Cob part of the mass when the humidity is high and Release it Back into your green house when

the humidity is low !

The word Cob is an Old English word for loaf -like a loaf of bread and Your Rocket is created one wet mass of Cob at a time !

In an ideal world we would build very small fires in our RMH to very slowly dry out our Cob, most new Pyro-Rocketeers just cant wait and suffer

through seeing water running out of their clean outs and seeing lots of steam in their Rockets Exhaust, We tell them its normal and will pas and

then they will see what a Healthy and Robust Dragon they have created !

Have a place outside of your humid greenhouse to store your wood and feed it the driest wood you can.

The 1st year if you only extend your growing season -ether end- by a couple of weeks things can only get better !

I lost track, how many Wins is that ? For the Good of the Craft ! Big AL
 
thomas rubino
Posts: 828
Location: latitude 47 N.W. montana zone 6A
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Lindsey; I'm entering my third season with a RMH in our greenhouse / studio. In short, it's everything I ever wanted out of a wood burner ! Last season in northern montana, I used just over 4 cord of wood!!! to keep our greenhouse 65+ everyday and 38+ or better every night with no fire from 10 at night till 7 or so next morning ! My old wood gobbler used 12-15 cords to do the same thing, only it was too hot or too cold most of the time and my wife would feed the stove till midnight and i would continue from 4 am on, not fun ! My RMH is an 8" J tube , all brick , barrel heavily cobbed, 14' long mass of cob & slate lasagna encased with a red brick surround ,with an indoor vertical chimney rising 14' to the peak. All parts of the room are comfy warm all the time ! no more hot & cold spots! Depending on the outside temps at the time , we do keep it going all day. Not as hard as some folks seem to think, once you have it going good every 40 minutes or so (wife uses a timer) we go out and refill the feed tube. A hot 8" core will easily burn a 6" red fir round with smaller sticks around it, this will last close to an hour but you will not get an optimum burn as it dies down. If your fire does go out... there is nothing easier than relighting a warm rmh ! Hardest part is relighting the lighter six times because the draft keeps sucking it out before you can get your paper relit. I now crumple up a piece in my hand , light it and then stuff it in the top of the feed tube... works perfect! When you let your feed tube burn out for the night, simply cover with extra brick to slow the draft and your mass will stay toasty warm all night . My greenhouse is 12x20 wood framed with a high peaked roof. We utilize a (mud room/entry way )to minimize exposure to the outside temps. Covered with solex and glass, with a dirt floor. We grow succulents rather than vegetables so we don't water much during the winter, so humidity isn't an issue. RMH's in greenhouses has its own post here at permies that will have lots of ideas for you, check it out.
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